Nanoscale titanium dioxide, TiO2, or titania, has outstanding properties which can be used in wide-ranging areas. For example, TiO2 can be used in heterogeneous catalysis, photocatalysis, solar cells, gas sensor, corrosion-protective coating, electrical devices such as varistors and so on. Thus, many TiO2 nanostructures, including hollow spheres, nanotubes, nanowires, and mesoporous structures have been synthesised.
Typically, TiO2 nanostructures are synthesised by chemical vapour deposition, microwave plasma torch, ultrasonic and electrochemical techniques. Other methods also used include electrospinning, sol-gel, and hydrolysis/alcoholysis of titanium precursors.
However, the most general and versatile solution-phase synthesis strategy is based on the hydrolysis and condensation of titanium alkoxides to create nanosized TiO2, with diameters from a few tens to several hundreds of nanometer. Owing to the very fast hydrolytic process at low temperature, this solution-phase synthesis strategy yields amorphous TiO2 products with polydisperse size and mixed phase, and subsequent hydrothermal processing or calcinations is necessary to induce crystallisation.
Thus, these methods are tedious and the nanostructures produced have average diameters larger than 10 nm, with the smallest at 3 nm.
It is desirable to provide a method for synthesising size-tunable, relatively thin wires down to the atomic scale. Such a method could possibly broaden the application scope and enhance utility of such nano-material.